Process of impregnating leather and leather substitute materials

ABSTRACT

A process for waterproofing leather or leather substitute articles comprises impregnating the articles with an organic solvent solution of a salt of a nitrogen-containing heterocyclic compound and a carboxylic acid having more than 21 carbon atoms.

United States Patent Heyden et al.

[451 Nov. 25, 1975 PROCESS OF IMPREGNATING LEATHER AND LEATHER SUBSTITUTE MATERIALS Inventors: Rudi Heyden, Hochdahl-Millrath;

Adolf Asbeck, Dusseldorf-Holthausen, both of Germany Henkel & Cie GmbH, Dusseldorf-Holthausen, Germany Filed: Oct. 6, 1972 Appl. No.: 295,457

Assignee:

Foreign Application Priority Data 2,872,428 2/1959 Schroeder 117/142 X 2,887,485 5/1959 Yost ll7/135.5 X 3,278,561 10/1966 Gaertner... 117/l35.5 X 3,475,206 10/1969 Heyden 117/142 OTHER PUBLICATIONS Marsh, An Introduction to Textile Finishing, Pub. 1948 by Chapman & Hall, Ltd., London, pp. 457, 458, 464 and 473-475.

Primary Examiner-Thomas J. Herbert, Jr. Attorney, Agent, or FirmHammond & Littell [57] ABSTRACT A process for waterproofing leather or leather substitute articles comprises impregnating the articles with an organic solvent solution of a salt of a nitrogencontaining heterocyclic compound and a carboxylic acid having more than 21 carbon atoms.

8 Claims, N0 Drawings PROCESS OF IMPREGNATING LEATHER AND LEATHER SUBSTITUTE MATERIALS PRIOR ART It is known from U.S. Pat. No. 3,475,206, to impregnate leather or leather substitute materials with organic solutions of salts of nitrogen-containing heterocyclic compounds such as basic imidazoline and/or pyrimi- 1O where R is a hydrocarbon radical with 9 to 20 carbon atoms, R is an alkylene with 2 to 3 carbon atoms; m is an integer of l to 3, and n is an integer of 2 or 3.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a process for the impregnation of leather or leather substitutes by utilizing solutions of salt from unsaturated or branchchained carboxylic acids having more than 21 carbon atoms with basic imidazoline and/or pyrimidine derivatives.

It is another object of the present invention to provide a process for waterproofing leather or leather substitutes which comprises impregnating leather or leather substitutes with an organic solution of a salt of a high-molecular-weight hydrocarbon carboxylic acid having to 30 carbon atoms and a basic nitrogen-containing heterocyclic compound selected from the group consisting of an imidazoline derivative and a pyrimidine derivative of the formula in which R is a higher hydrocarbon radical having 9 to 29 carbon atoms, with the proviso that whenever the carboxylic acid has no more than 21 carbon atoms then R has more than carbon atoms; R is an alkylene having 2 to 3 carbon atoms, m is an integer from 1 to 3 and n is an integer from 2 to 3.

Other and further objects of the invention will become apparent as the description thereof proceeds.

DESCRIPTION OF THE INVENTION The present invention is directed to a process for waterproofing leather or leather substitutes which comprises impregnating leather or leather substitutes with an organic solution of a salt of a high-molecular-weight hydrocarbon carboxylic acid having 10 to carbon atoms and a basic nitrogen-containing heterocyclic compound selected from the group consisting of an imidazoline derivative and a pyrimidine derivative of the formula in which R is a higher hydrocarbon radical having 9 to i 29 carbon atoms, with the proviso that whenever the carboxylic acid has no more than 21 carbon atoms then R has more than 20 carbon atoms; R is an alkylene having 2 to 3 carbon atoms, m is an integer from 1 to 3 and n is an integer from 2 to 3.

Generally speaking, either the carboxylic acid has more than 21 carbon atoms or the grouping R,C will have more than 21 carbon atoms, or both the carboxylic acid and the grouping R,C will have more than 21 carbon atoms, according to the invention. However both the carboxylic acid and the grouping R,C cannot have less than 21 carbon atoms each, in the same compound.

It has been found, surprisingly, that by utilizing compounds wherein either the carboxylic acid utilized to form the salt or that utilized to form the basic heterocyclic compound or both have more than 21 carbon atoms considerable improvements over the products of U.S. Pat. No. 3,475,206 are obtained. The products of the present process have the advantage that the dynamic waterproofness of the treated leathers or leather substitutes increases significantly. In particular the impregnating process is suitable for all leathers tanned with natural tanning substances, synthetic tanning substances or metal salts as well as for synthetic leather, such as artificial leather made from leather waste, porous plastics with leather character, and other porous or fibrous materials used as imitiation leather.

The production of the imidazoline or pyrimidine derivatives is described in the disclosure of U.S. Pat. No. 3,475,206. The starting materials are higher-molecular-weight carboxylic acids, which are condensed with polyalkylene polyamines, such as diethylene triamine, triethylene tetramine, or dipropylene triamine, at an elevated temperature, with the water formed in the reaction being removed by distillation. The salt formation occurs in a known manner by neutralization of the condensation product with a carboxylic acid of the desired structure or chain length.

According to the present invention, carboxylic acids with more than 21 carbon atoms are utilized for the condensation and/or the neutralization steps. Examples of preferred carboxylic acids are those which contain from 22 to 30, preferably from 22 to 26 carbon atoms, for example those which are unsaturated, for example alkenoic acids of 22 to 26 carbon atoms such as erucic acid, hydroxyalkenoic of 22 to 26 carbon atoms, alkadienoic acids of 22 to 26 carbon atoms, and alkatrienoic acids of 22 to 26 carbon atoms, and the mixtures thereof, Other preferred carboxylic acids contain branch-chained alkyl substituents and these acids have 22 to 26 carbon atoms, or phenyl alkanoic acids of 22 to 26 carbon atoms, such as phenylstearic acid, and the mixtures thereof. Particularly effective carboxylic acids are erucic acid and omega-phenylstearic acid. However, other higher-molecular-weight carboxylic acids, in particular unsaturated or branch-chained carboxylic acids, such as resinic acids, montanic acids or the branch-chained carboxylic acids obtained by oxidation of branch-chained paraffins with more than 21 carbon atoms, may be used.

The carboxylic acids used for carrying out the condensation reaction and the salt formation reaction may be identical or different. It is also possible to use naturally occurring fatty acids of the claimed chain lengths, as well as the mixtures thereof, or in combination with other carboxylic acids.

It has been found that the dynamic waterproofness of leather and leather substitutes can be substantially increased (A) when the carboxylic acid utilized for the salt formation neutralization reaction contains more than 21 carbon atoms according to the invention, while the carboxylic acid used for the condensation reaction contains from to 21 carbon atoms according to US. Pat. No. 3,475,206; or (B) when the carboxylic acid utilized for the condensation reaction contains more than 21 carbon atoms according to the invention, while the carboxylic acid used for the salt formation neutralization reaction contains from 10 to 21 carbon atoms according to the prior art.

Examples of suitable impregnating agents are the salt of a higher 'carboxylic acid of more than 21 carbon atoms with the condensation product of said acid and an aliphatic amine of the formula NH [(CH ),,NH- ],,H, in which p 2 to 3 and q 2 to 4, such as the salt of erucic acid with the condensation product from diethylene triamine and erucic acid, the salt of omegaphenylstearic acidwith the condensation product from diethylene triamine and omega-phenylstearic acid, the salt from oleic acid with the condensation product from diethylene triamine and omega-phenylstearic acid, and the salt from erucic acid with the condensation product from triethylene tetramine and oleic acid. The salts are readily soluble in organic solvents, for example aliphatic hydrocarbons, aromatic hydrocarbons, chlorinated hydrocarbons, for example chlorinated alkylenes such as trichloroethylene, or alcohols for example lower alkanols such as isopropanol and the mixtures thereof, resulting in solutions of low viscosity. These products are practically insoluble in water; however, they swell intensively in the presence of water.

A further improvement of the impregnation effect can be obtained by combining the products according to the present invention with partially esterified or partially etherified poly-alcohols or partially esterified polycarboxylic acids which contain at least one unsaturated or branch-chained grouping with 8 to 22 carbon atoms. Especially preferred compounds of this group are the glycerin and pentaerythrite partial esters of the higher fattyacids of 8 to 22 carbon atoms, in particular oleic acid. Also especially preferred are citric acid mono-oleyl esters.

The impregnation is carried out either by immersing the leather in the organic solutions containing about 5% to 30% by weight of the products or by applying the solution directly to the leather such as by spreading, brushing or spraying thereon. Even in the presence of relatively low quantities of water, the alcoholic solutions of these salts maintain their low viscosity, such that the desired impregnation effects can be obtained by fulling the alcoholic solutions into the still moist leather in the tanning barrel.

The products of the invention are noted for possessing a considerable water binding and swelling capacity. This activity is probably based on the formation of viscous or pasty water-in-oil emulsions within the fiber interstices of the leather. Thus whenever the impregnated leather is contacted by a very slight amount of moisture the pores are closed and resistance is offered to the further penetration of water into the leather. Accordingly, the passage of water through the leather is not only greatly retarded, but the absorption of water into the leather is also reduced.

A special advantage of the present products is their stability within the leather toward repeated wetting. Even after many hours of mechanically stressing the wet leather containing the present impregnating agent, this impregnating agent is not washed out. To enhance the effect of the impregnation agents or to achieve special effects, certain known impregnating agents, greasing agents, silicones or the like can be used as well.

The following examples are merely illustrative of the present invention without being deemed limitative in any manner thereof.

EXAMPLE 1 In order to provide a basis for determining the waterproofing effect after impregnation of the leather or leather substitute, the following products A, B, and C were prepared:

Product A 32.9 parts by weight of phenylstearic acid and 9.5 parts by weight of diethylene triamine were heated while stirring. Elimination of water started at 150C; and the temperature was increased to 220C. After the condensation reaction was completed, 32.9 parts by weight of phenylstearic acid were added to neutralize the basic condensation product, to give Product A.

Product B Phenylstearic acid and diethylene triamine were reacted according to the procedure as described for Product A. The reaction product was neutralized with 25.8 parts by weight of oleic acid to given Product B.

Product C 25.8 parts by weight of oleic acid were heated together with 9.5 parts by weight of diethylene triamine while stirring. The elimination of water started at 140C; and the temperature was slowly increased to 220C. After the condensation reaction was completed,

' 32.9 parts by weight of phenylstearic acid were added to neutralize the basic condensation product, to give Product C.

Reference Product D According to Example 1 B of the German Pat. No.

1,273,122, a condensation product from oleic acid and diethylene triamine was produced and neutralized with oleic acid to give Product D. This prior art product served for comparison with the Products A, B and C according to the present invention.

The Products A to D were dissolved in the weight ratio 1:4 in an equal parts by volume mixture of trichloroethylene and isopropanol. With these solutions, two different bottom leathers (I and H), tanned by a vegetable type synthetic tanning agent, were impregnated by immersing these leathers for 15 minutes in said solutions and then drying then in air for about 24 hours. Following this they were dried further by heating for 2 hours to about 50C in the drying cabinet (designation of the impregnated leathers l A, I B. etc., II A, II B, etc.).

The leathers were tested according to the official standards for testing the dynamic waterproofness of sole leather (Das Leder" 1961, 12, p. 64).

In addition the tested wet leather pieces were dried in air and the test was repeated, to determine how well the impregnation waterproofing can withstand simulated conditions most closely resembling those occurring during the actual practice of wearing shoes (designation of these leather samples IA 1, 1B 1, etc., IIA 1, 11B 1, etc.). Thereafter the leathers were dried once more and again tested (designation of these leather samples IA 2, IB 2, etc., IIA 2, I18 2, etc.) The results are shown in the following Table I.

TABLE I Leather Water Penetration Water Absorption in after Min. 1 hr. 2 hr. 3 hr.

1A 72 3.1 8.5 11.3 [B 115 3.5 4.9 6.4 1C 83 6.3 10.5 11.8 ID 53 8.2 12.5 13.5 1A1 230 8.0 13.5 15.4 1B 1 480 7.5 11.1 13.8 IC 1 250 10.2 13.2 19.6 1D1 64 13.0 18.1 21.2 1A 2 425 8.0 14.1 19.2 18 2 500 7.2 11.7 17.0 1C 2 150 11.6 20.8 27.0 ID 2 128 11.1 18.2 24.5 11A 480 6.9 12.0 15.4 118 480 4.2 5.4 6.5 IIC 480 6.1 10.6 14.4 IID 480 5.9 8.1 10.1 11A 1 480 2.4 6.5 8.9 118 1 480 6.1 8.4 10.2 11C 1 480 11.0 17.5 21.2 "D 1 480 10.2 15.6 19.6 11A 2 480 12.8 16.0 17.7 1113 2 480 6.2 8.4 10.2 IIC 2 480 17.5 22.8 24.2 IID 2 75 17.4 21.9 24.3

The results clearly show the superiority of the Products A, B and C of the invention over Product D.

EXAMPLE 2 It is known that such leathers of firm structure give relatively low values in the dynamic test for water tightness. The test results are reported in Table 11.

TABLE II Leather Water Penetration After Minutes B 250 C 220 D 78 This test demonstrates that leather impregnated with the products according to the process of the invention has an improved waterproofing under dynamic testing for water tightness of from about 2.8 to 3.2 times, or approximately 3 times the waterproofing according to 6 the prior art. The superiority of the Samples B and C over Sample D is evident.

EXAMPLE 3 Product E Utilizing a procedure analogous to that described above for Example 1, 26.3 parts by weight of erucic acid and 8.5 parts by weight of diethylene triamine were reacted at a temperature ranging up to 220C; and then the condensation reaction product was neutralized at 1 10C with 26.3 parts by weight of erucic acid to give Product E.

Retanned chrome upper leather was impregnated, as described in Example 2, with solutions of the impregnation agents B and E, and with Product D for comparison. The impregnated leathers were tested according to the method common in the U.S.A.., described by Maeser (J. American Leather Chemists Assoc., 42, 390

This test demonstrates that leather impregnated with products according to the process of the invention has an improved waterproofing under dynamic testing for water tightness of from about 2.7 to 4.2 times, or approximately 3.5 times the waterproofing according to the prior art. The superiority of the Samples B and E over Sample D is evident.

Although the present invention has been disclosed in connection with a few preferred embodiments thereof, variations and modifications may be resorted to by those skilled in the art without departing from the principles of the new invention. All of these variations and modifications are considered to be within the true spirit and scope of the present invention as disclosed in the foregoing description and defined by the appended claims.

We claim:

1. A process for waterproofing leather or leather substitutes which comprises impregnating leather or leather substitutes with an organic solution of a salt of a high-molecular-weight hydrocarbon carboxylic acid selected from the group consisting of erucic acid and omega-phenylstearic acid and a basic nitrogen-containing heterocyclic compound selected from the group consisting of an imidazoline derivative and a pyrimidine derivative of the formula in which R is a higher hydrocarbon radical derived from a carboxylic acid selected from the group consisting of erucic acid and omega-phenylstearic acid, R is an alkylene having 2 to 3 carbon atoms, m is an integer from 1 to 3, and n is an integer from 2 to 3.

2. The process of claim 1, in which the organic solution contains from about 5% to 30% by weight of said salt in an organic solvent selected from the group consisting essentially of aliphatic hydrocarbons, aromatic hydrocarbons, chlorinated hydrocarbons, alcohols, and the mixtures thereof.

3. Waterproof leather and synthetic leather prepared by the process of claim 1.

4. The process of claim 1, wherein said high-molecular-weight hydrocarbon carboxylic acid is erucic acid and wherein said higher hydrocarbon radical is derived from erucic acid.

5. The process of claim 1, wherein said high-molecular-weight hydrocarbon carboxylic acid is omegaphenylstearic acid and wherein said higher hydrocarbon radical is derived from omega-phenylstearic acid.

in which R is a higher hydrocarbon radical derived from a carboxylic acid selected from the group consisting of erucic acid and omega-phenylstearic acid, R is an alkylene having 2 to 3 carbon atoms, m is an integer from 1 to 3 and n is an integer from 2 to 3, said nitrogen-containing heterocyclic compound being the condensation product of an aliphatic amine of the formula z"[( z)| ]s in which p is an integer from 2 to 3 and q is an integer from 2 to 4, with said carboxylic acid selected from the group consisting of erucic acid and omega-phenylstearic acid.

7. The process of claim 6, in which the aliphatic amine is a polyalkylene polyamine selected from the group consisting of diethylene triamine, triethylene tetramine, and dipropylene triamine.

8. The process of claim 6, in which the organic solution contains from about 5% to 30% by weight of said salt in an organic solvent selected from the group consisting essentially of aliphatic hydrocarbons, aromatic hydrocarbons, chlorinated hydrocarbons, alcohols, and

the mixtures thereof. 

1. A PROCESS FOR WATERPROOFING LEATHER OR LEATHER SUBSTITUTES WHICH COMPRISES IMPREGNATING LEATHER OR LEATHER SUBSTITUTES WITH AN ORGANIC SOLUTION OF A SALT OF A HIGH-MOLECULAR-WEIGHT HYDROCARBON CARBOXYLIC ACID SELECTED FROM THE GROUP CONSISTING OF ERUCIC ACID AND OMEGA-PHENYLSTEARIC ACID AND A BASIC NITROGEN-CONTAINING HETEROCYCLIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF AN IMIDAZOLINE DERIVATIVE AND A PYRIMIDINE DERIVATIVE OF THE FORMULA
 2. The process of claim 1, in which the organic solution contains from about 5% to 30% by weight of said salt in an organic solvent selected from the group consisting essentially of aliphatic hydrocarbons, aromatic hydrocarbons, chlorinated hydrocarbons, alcohols, and the mixtures thereof.
 3. Waterproof leather and synthetic leather prepared by the process of claim
 1. 4. The process of claim 1, wherein said high-molecular-weight hydrocarbon carboxylic acid is erucic acid and wherein said higher hydrocarbon radical is derived from erucic acid.
 5. The process of claim 1, wherein said high-molecular-weight hydrocarbon carboxylic acid is omega-phenylstearic acid and wherein said higher hydrocarbon radical is derived from omega-phenylstearic acid.
 6. A process for waterproofing leather or leather substitutes which comprises impregnating leather or leather substitutes with an organic solution of a salt of a high-molecular-weight hydrocarbon carboxylic acid selected from the group consisting of erucic acid and omega-phenylstearic acid and a basic nitrogen-containing heterocyclic compound selected from the group consisting of an imidazoline derivative and a pyrimidine derivative of the formula
 7. The process of claim 6, in which the aliphatic amine is a polyalkylene polyamine selected from the group consisting of diethylene triamine, triethylene tetramine, and dipropylene triamine.
 8. The process of claim 6, in which the organic solution contains from about 5% to 30% by weight of said salt in an organic solvent selected from the group consisting essentially of aliphatic hydrocarbons, aromatic hydrocarbons, chlorinated hydrocarbons, alcohols, and the mixtures thereof. 